Ive been with dodge since 2000ish, I cant get a HONEST answer out of anyone in engineering. So my father in law bought a 17 RAM Rebel. its his good truck, dosnt drive it every day. Its been average of 95 plus here lately. in this truck I use the big filter, and run the synthetic oil we sell at the dealership. 5W20 penzoil platinum oil.

HERENDOUS lifter clatter on start up. I mean like a 30 second count. Im convinced its oil drain back in the HOT ambient temps.

Our 6.4 hemi in the 3/4 ton didn't do this, but it ran 0W40 synthetic. It also had MDS...

Is it possible to run the 0W40 in the 5.7 to possibly keep this thin as PISS oil from draining back so bad?

Oh and theres several trucks on our lot, one a 5.7 Rebel that does the same thing.

On another ram forum that I visit many have changed oil weights and report no issues. Most I see go to 5w30 (redline and others) and they say it quiets the engine. I haven`t tried it yet. My 2014 clatters for a few seconds on start up and I`m using 5w20 PUP. I`m going to try 5w30 for the summer.

Your magnum wont have MDS, that started in the Hemi engines around 07, 08 in the cars and some SUVs.

The viscosity code is bogus cause even our owners manuals say to run a heavier oil in extreme heat or climates that get up above the triple digits

I know of more than one person running the heavier oils in their trucks, and LX cars and it really just slows down the MDS activation. It will throw a cam phaser time rationality code.

I finally got back with my Engineer buddy, and we talked on the phone for quite a while. He said to try the 0W40, and the only difference between the 5.7 and the 6.4s MDS is programing. They allow a longer time to see a cam phaser change VS the 5.7 so with that theres a chance I see an issue but Ill try it.

My 04 ram doesn't have mds, I had the heads shave 20 thousands before putting that engine back together with stock length pushrods... no lifter noise at all from it. Always thought about trying slightly longer pushrods in another and see if it does the same. Not sure how it would work with mds lifters though.

I also read about the redline 5w 30 working in place of 5w 20, but I never tried. I know for sure 10w30 even in mid summer heat will throw a code. I tried it last summer. I changed back to 5w20 and it went away... had to get emissions done and couldn't have a check engine light on.